Spherical Mirrors
Chapter Name : Light-Reflection And Refraction |
Sub Topic Code : 101_10_10_02_04 |
Topic Name : Spherical Mirrors |
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Sub Topic Name : Sign Convention For Reflection By Spherical Mirrors |
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Introduction
We follow a specific sign convention in order to use the distances in the calculations.
Pre-Requisites:
An introduction about Cartesian sign convention, and image formation by spherical mirrors.
Activity:
Take any mirror and see the image of an object placed at the different positions and compare the results with the results from ray diagram and comment on the sign of the various distances.
Real Life Question:
“Why image formed by convex lens is virtual?”
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Cartesian system | A mathematical system of representation in which all distances left to the center are negative and right to the center are positive. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Any curved mirror | Place the object at various positions and observe the image formed. |
Real life uses :
Concave mirrors are used in headlights of cars; dentist uses this type of mirror. While convex mirror is used in making sunglasses and also used in telescopes.
Places to visit :
Hallways of various buildings, Mirror mazes, fun houses,
Practical examples around us
| Examples | Explainations |
|---|---|
| Torches | Concave mirrors are used the torches to concentrate the light at one place. |
| ATMs | Convex mirrors are used in ATMs to see the happenings behind them. |
| Telescopes | Convex mirrors are used in the telescopes as well. |
What you learn in Theory:
All the distances measured to the right of the origin (along + x-axis) are taken as positive while those measured to the left of the origin (along – x-axis) are taken as negative. Distances measured perpendicular to and above the principal axis (along + y-axis) are taken as positive. Distances measured perpendicular to and below the principal axis (along –y-axis) are taken as negative.
What you learn in Practice:
Curved mirrors are very useful in day to day life. They are used in various instruments. Also they can be used directly to serve a purpose.